JPH11236991A - Pipe fitting manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a pipe joint which requires a small processing cost, can be manufactured without a step on a fusion surface when fusion is performed, and does not reduce mechanical strength. SOLUTION: A pipe joint or a pipe body made of a thermoplastic resin is cut, and cut surfaces of two members obtained by cutting such that the vicinity of the cut surface has a substantially uniform thickness are fused.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a pipe joint.

[0002]

2. Description of the Related Art Conventionally, sockets, cheeses, cloths,
Pipe fittings formed into elbows and other various shapes are usually manufactured by injection molding.

[0003] However, in the case of such a pipe joint, since it is integrally formed by injection molding or the like, every time the diameter of the resin pipe changes, a pipe joint suitable for the diameter is required. Therefore, in order to prepare a large number of fittings for various pipelines, all of these fittings must be manufactured in separate molds. In addition, it must be finished precisely so as not to have burrs, and very expensive equipment and dies are required. In particular, in the case of joints such as cloths and elbows, which have a large number of varieties and a small number of products produced per kind, the cost is high.

[0004] Therefore, a method of diagonally cutting relatively mass-produced cheese or the like, fusing the cut surfaces together, and producing a pipe joint having a small number of pieces produced per kind, such as a cloth or an elbow, can be considered.

[0005]

However, when a cheese or the like is cut obliquely and one of them is rotated by 180 ° to be fused, a step is generated in the fused surface, and the notch effect causes There is a problem that mechanical strength such as hot creep is reduced.

An object of the present invention is to provide a method of manufacturing a pipe joint which solves the above-mentioned problems, requires a low processing cost, can be manufactured without any step on a fusion surface when fusion is performed, and does not reduce mechanical strength. Aim.

[0007]

According to a first aspect of the present invention, there is provided a pipe joint manufacturing method (hereinafter referred to as "the present invention 1") which cuts a pipe joint or a tubular body made of a thermoplastic resin, and cuts the vicinity of the cut surface. Are used to fuse the cut surfaces of two members obtained by cutting so as to have a substantially uniform thickness.

The pipe joint used in the present invention 1 is, for example, a T-shaped cheese (hereinafter simply referred to as “cheese”);
Socket; 4-way joints such as cloth and offset cloth;
A joint having a bent portion (hereinafter, referred to as an “elbow”) is exemplified. Particularly, cheeses and sockets that are produced in large numbers are preferably used.

As the material of the pipe or the pipe joint used in the present invention 1, a thermoplastic resin used for ordinary injection molding and extrusion molding is used. For example, olefin resins such as polyethylene and polypropylene; vinyl chloride Acrylic resin; acrylonitrile-butadiene-styrene copolymer;

The pipe or the pipe joint used in the present invention 1 is formed by using the above-mentioned thermoplastic resin in advance by a conventionally known method such as an injection molding method or an extrusion molding method.

A method for manufacturing a pipe joint according to claim 2
This is referred to as "the present invention 2". ) Has two main pipes and one branch pipe branched from the main pipe, and the branch portion of the cheese formed of the thermoplastic resin is approximately 45 ° away from the center line of the main pipe.
A member 2 having a branch pipe obtained by cutting at an angle of
After cutting the pieces so that the thickness near the cut surface is substantially uniform, the cut surfaces are fused together to obtain a four-way joint.

The material of the cheese used in the present invention 2 is the same as that of the present invention. In the second aspect of the present invention, the method of making the thickness near the cut surface substantially uniform is not particularly limited, and a normal lathe or the like is used. The four-way joint obtained in the second aspect of the present invention includes, for example, a cross and an offset cross.

[0013] The method for manufacturing a pipe joint according to claim 3 (hereinafter referred to as "the method").
This is referred to as "the present invention 3". In the method for manufacturing a pipe joint according to the second aspect of the present invention, the cutting position is slightly shifted from the intersection of the center line of the main pipe and the branch pipe to the side opposite to the branch pipe.

The distance from the intersection of the center line of the main pipe and the branch pipe of the cheese to the cut surface is not particularly limited, and varies depending on the size of the cheese. However, in order to generate a uniform bead at the time of welding, it is necessary to cut the cheese. In consideration of the cutting allowance for smoothing the surface and the fusion allowance at the time of fusion, the thickness is preferably 5 to 20 mm, and more preferably 10 to 15 mm. It is preferable that the distance from the intersection of the center lines of the main pipe and the branch pipe of the two cheeses to the cut surface is substantially equal.

The method for fusing the cut surfaces in the present invention 2 or 3 is not particularly limited. For example, the cut surfaces are pressed against each other while sandwiching a heating plate, and after the cut surfaces are melted, once removed. Pressure to melt the cut surface sufficiently, then remove the heating plate, bring the melted cut surfaces into contact with each other, press from perpendicular to the cut surface and fuse to produce a certain amount of beads And the like.

[0016] The method for manufacturing a pipe joint according to claim 4 (hereinafter referred to as "the pipe joint").
This is referred to as "Invention 4". ) Has two main pipes and one branch pipe branched from the main pipe, and is a side having no branch pipe obtained by cutting a branch portion of a T-shaped cheese formed of a thermoplastic resin. Are cut so that the wall thickness in the vicinity of the cut surface becomes uniform, and the cut surfaces are fused together to obtain a joint having a bent portion (hereinafter referred to as “elbow”). .

In the present invention 4, the cheese used and the material thereof are the same as those of the present inventions 1 to 3, and the rest of the cheese used in the present invention 2 or 3 may be used. Further, the remaining portion of the cheese used in the present invention 2 or 3 may be cut again.

The method of making the thickness near the cut surface uniform is the same as in the first to third inventions.

In manufacturing an elbow fitting using the method of the fourth aspect of the present invention, the angle cut with respect to the center line of the main pipe is 1/2 of the desired angle of the elbow, and The angles are usually 90 °, 45 °, 22.5 °, 11.25
°, the cutting angles are 45 ° and 2
2.5 °, 11.25 °, and 5.625 °. Of course,
Angles other than these can also be accommodated.

In the present invention 4, the method of fusing the cut surfaces is not particularly limited. For example, the cut surfaces are pressed against each other while sandwiching a heating plate, and after the cut surfaces are melted, the pressure is temporarily reduced. Then, the cut surface is sufficiently melted, and then the heating plate is removed, the melted cut surfaces are brought into contact with each other, pressed from a direction perpendicular to the cut surface and fused to remove the beads.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing an example of the cheese used in the present inventions 1 to 3. In FIG. 1, a T-shaped cheese 1 has two main pipes 2, 2 ′ and a main pipe 2,
It is made of injection molded polyethylene and has one branch pipe 3 branched from 2 '.

First, as shown in FIG. 1, the pipe joint manufacturing method according to the first to third embodiments of the present invention uses the branch pipe 3 from the intersection P of the center lines of the main pipes 2 and 2 'and the branch pipe 3 in the branch portion 22. From the position slightly shifted to the opposite side, the cutting is performed at the cutting surface 4 at an angle of about 45 ° with respect to the center line of the main pipes 2 and 2 ′. Branch pipe 3 obtained by cutting
FIG. 2 shows the shape of the member 1 ′ having the side (hereinafter, simply referred to as “member 1 ′”).

FIG. 3 is a side view showing the cut surface 4 of the member 1 ′ having the branch pipe 3, and shows the thickness of the cut surface 4. Then, the vicinity of the cut surface 4 of the member 1 'is cut by a lathe until the thickness becomes the minimum value (32.0 mm) shown in FIG. The cut surface after cutting is shown by a broken line in FIG.

FIG. 4 is a side view showing an example of an apparatus for manufacturing a pipe joint used in the present inventions 1 to 3, and includes members 1 'and 1'.
Are to be fused together. As shown in FIG. 4, the apparatus for manufacturing a pipe joint includes a fixed mold plate 5 and a movable mold plate 6, and a fixed mold plate 5 and four pressing plates 7 fixed to the movable mold plate 6. In the method for manufacturing a pipe joint according to the first or second aspect of the present invention, first, the cut surfaces of the members 1 ′ and 1 ′ face each other with the heating plate 8 heated above the melting point of the members 1 ′ and 1 ′ facing each other. The movable mold plate 6 is moved rightward in FIG. 4 by a hydraulic mechanism (not shown), and the members 1 ′ and 1 ′ are pressed from a direction perpendicular to the cut surface.

Next, after the cut surface is melted, the pressure is temporarily reduced to sufficiently melt the cut surface. When the cut surface is sufficiently melted, the movable mold plate 6 is moved to the left in FIG. 4 to remove the heating plate 8, and immediately (preferably within 5 seconds, at most 7 seconds) again. Is moved rightward in FIG. 4 so that the cut surfaces are brought into contact with each other, and pressed from a direction perpendicular to the cut surface to fuse them.

FIG. 5 shows the pipe joint immediately after fusion in the present invention 1 or 2, (a) is a side view thereof, and (b) is a sectional view thereof. As shown in FIG. 5, the main pipe 2 shown in FIG.
The bead 9 is generated by 1/3 to 1/2 of the distance from the intersection P of the 2 'and the center line of the branch pipe 3 to the side opposite to the branch pipe 3, and the cross pipe joint 10 is manufactured.

FIG. 6 is a side view showing an example of a member having no branch pipe used in the present invention 4. As shown in FIG. In this example, the remaining portion of the cheese cut in FIG. 1 on the main pipe 2 'side (hereinafter, simply referred to as "member 11") is used as it is.

FIG. 7 is a side view showing an example of a pipe joint manufacturing apparatus used in the present invention 4, in which cut surfaces of members 11, 11 are fused together. As shown in FIG. 7, the pipe joint manufacturing apparatus includes a fixed mold plate 15 and a movable mold plate 16, and a fixed mold plate 15 and four pressing plates 17 fixed to the movable mold plate 16. In the method for manufacturing a pipe joint of the present invention 3 or 4, first, the cut surfaces of the members 11 and 11 are attached to the pressing plate 17 with the cut surfaces of the members 11 and 11 facing each other with the heating plate 18 heated above the melting point of the members 11 and 11 interposed therebetween. The members 11, 11 are moved from the direction perpendicular to the cut surface by moving the movable mold plate 16 to the right in FIG. 4 by a hydraulic mechanism (not shown).

Next, after the cut surface is melted, the pressure is temporarily reduced to sufficiently melt the cut surface. When the cut surface is sufficiently melted, the movable mold plate 16 is moved to the left in FIG. 7 to remove the heating plate 18, and the movable mold plate 16 is moved again to the right in FIG. Are brought into contact with each other and pressed from a direction perpendicular to the cut surface to be fused to generate the beads 19 uniformly, thereby obtaining the elbow pipe joint 20 having the shape shown in FIG.

[0030]

The present invention will be described in more detail with reference to the following examples. (Example 1) Two cheeses of a polyethylene gas pipe joint (JIS K6795 equivalent, nominal diameter 150 mm) molded by injection molding shown in FIG.
7m from the intersection P of 2 'and the center line of the branch pipe 3 to the side opposite to the branch pipe 3
Starting from the position shifted by m, the main pipes 2 and 2 ′ were cut at a cut surface 4 at an angle of 45 ° with respect to the center line to obtain two cut members 1 ′ shown in FIG.

The dimensions of the cross section of the cut member 1 'are as shown in FIG. Therefore, the vicinity of the cross section 4 was uniformly cut to a thickness of 32.0 mm by a lathe as shown by a dotted line in FIG. 3, and then the heating plate 8 heated to 210 ° C. as shown in FIG.
Is mounted between the pressing plates 7 so that the cut surfaces of the members 1 ′ and 1 ′ face each other, and the movable mold plate 6 is moved rightward in FIG. 1. From right angle direction
It was pressed at 25 kgf / cm ² for 30 seconds to melt the cut surface.

Then, after the cut surface is melted,
The pressure was reduced to kgf / cm ² and the cut surface was sufficiently melted for 90 seconds. Then, the movable mold plate 6 is moved to the left in FIG. 4, the heating plate 8 is removed, and the movable mold plate 6 is immediately moved again to the right in FIG. It was pressed at 1.25 kgf / cm ² for 90 seconds from the direction perpendicular to the surface to fuse. At this time, a bead 9 having a width of 3.5 mm was generated as shown in FIG. 5, and a cross pipe joint 10 was obtained.

(Embodiment 2) Embodiment 1 having the shape shown in FIG.
The remaining two pieces (member 11; main pipe 2 'side) of the cheese cut in step 2 were prepared, and the lathe was used as shown in FIG.
After being uniformly cut to a thickness of 2 mm, as shown in FIG.
Cheese 11, 1 with heating plate 18 heated to 10.degree.
1 is mounted between the pressing plates 17 with the cut surfaces facing each other, the movable mold plate 16 is moved rightward in FIG.
1.25 kgf / c from the direction perpendicular to the cut surface of No. 11
It was pressed for 30 seconds at m ² to melt the cut surface.

Next, after the cut surface is melted, once 0.1 mm
The pressure was reduced to kgf / cm ² and the cut surface was sufficiently melted for 90 seconds. Then, the movable mold plate 16 is moved to the left in FIG. 7 to remove the heating plate 18 and immediately again move the movable mold plate 1.
6 is moved rightward in FIG. 7 so that the cut surfaces come into contact with each other.
The sheet was pressed at 1.25 kgf / cm ² for 90 seconds from a direction perpendicular to the cut surface to perform fusion. At this time, a bead 19 having a width of 3.5 mm was generated as shown in FIG. 8, and a pipe joint of an elbow 20 was obtained.

Comparative Example 1 A cross pipe joint was obtained in the same manner as in Example 1 except that the members 1 'and 1' were not cut by a lathe.

Comparative Example 2 An elbow joint was obtained in the same manner as in Example 1, except that the members 11 and 11 were not cut by a lathe.

Each of the three pipe joints obtained in Examples 1 and 2 and Comparative Examples 1 and 2 was subjected to a long-term hot internal pressure creep test according to JIS K6775, and defects such as cracks were visually determined. As a result, there were no more than three pipe joints in Examples 1 and 2, whereas the pipe joint of Comparative Example 1 was two pipe joints, and the pipe joint of Comparative Example 2 was three pipe joints. Cracks were detected in all.

[0038]

The method for manufacturing a pipe joint according to the first aspect of the present invention is obtained by cutting a pipe joint or a pipe made of a thermoplastic resin and cutting the pipe joint so as to have a substantially uniform thickness in the vicinity of the cut surface. Since the cut surfaces of the two members are fused together, it is possible to obtain a pipe joint that does not require an expensive mold, can be manufactured at low cost, and does not decrease in mechanical strength.

The method of manufacturing a pipe joint according to the second aspect of the present invention has two main pipes and one branch pipe branched from the main pipe, and the branch part of the cheese formed of the thermoplastic resin is moved to the center line of the main pipe. After cutting the two members on the side having the branch pipe obtained by cutting at an angle of about 45 ° so that the thickness near the cut surface is substantially uniform, the cut surfaces are separated from each other. Since fusion is performed, a four-way joint that does not require an expensive mold and can be manufactured at low cost and that does not reduce mechanical strength can be obtained.

The manufacturing method of the pipe joint according to the third aspect of the present invention
In the method of manufacturing a pipe joint according to the above, the cutting position is slightly shifted from the intersection of the center line of the main pipe and the branch pipe to the side opposite to the branch pipe. , A four-way joint with good dimensional accuracy can be obtained.

The method of manufacturing a pipe joint according to the fourth aspect of the present invention has two main pipes and one branch pipe branched from the main pipe, and is obtained by cutting a branch portion of a cheese formed of a thermoplastic resin. In addition, after cutting two members on the side having no branch pipe so that the wall thickness near the cut surface becomes uniform, the cut surfaces are fused together, so that an expensive mold is required. Thus, a four-way joint that can be manufactured at low cost and that does not reduce the mechanical strength can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view showing an example of cheese used in the present inventions 1 to 3.

FIG. 2 is a side view showing the shape of a member having a branch pipe.

FIG. 3 is a side view showing a cut surface of a member having a branch pipe, and shows a thickness of the cut surface.

FIG. 4 is a side view showing an example of a pipe joint manufacturing apparatus used in the present inventions 1 to 3.

FIGS. 5A and 5B show an example of a pipe joint obtained by the present inventions 1 to 3, wherein FIG. 5A is a side view thereof, and FIG. 5B is a sectional view thereof.

FIG. 6 is a side view showing an example of a member having no branch pipe used in the present invention 4.

FIG. 7 is a side view showing an example of a pipe joint manufacturing apparatus used in the present invention 4.

FIG. 8 is a side view showing an example of the pipe joint obtained in the fourth invention.

[Explanation of symbols]

 Reference Signs List 1 cheese 1 'member having branch pipe 11 member not having branch pipe 2' main pipe 22 branch part 3 branch pipe 4 cutting surface 8, 18 heating plate 9, 19 beat

Claims (4)

[Claims] 1. A pipe joint or pipe made of a thermoplastic resin is cut, and cut surfaces of two members obtained by cutting such that the vicinity of the cut surface becomes substantially uniform in thickness are fused. A method for manufacturing a pipe joint, comprising: 2. A T-shaped cheese branch made of a thermoplastic resin, having two main pipes and one branch pipe branched from the main pipe, and having a T-shaped cheese branched at approximately 45 ° with respect to a center line of the main pipe. Two members on the side having a branch pipe obtained by cutting at an angle of
A method for manufacturing a pipe joint, characterized in that after cutting such that the thickness in the vicinity of the cut surface is substantially uniform, the cut surfaces are fused to obtain a four-way joint. 3. The method of manufacturing a pipe joint according to claim 2, wherein the cutting position is a position slightly shifted from an intersection of a center line of the main pipe and the branch pipe to a side opposite to the branch pipe. 4. A branch pipe having two main pipes and one branch pipe branched from the main pipe and obtained by cutting a branch portion of a T-shaped cheese formed of a thermoplastic resin. Manufacturing a pipe joint characterized by cutting two members on the side not to be cut so that the wall thickness near the cut surface becomes uniform, and then fusing the cut surfaces together to obtain a joint having a bent portion. Method.